This invention relates to a method of wrapping elongate articles such as pipes, rods, tubes and the like elements, which may be substantially straight through-out their length, or of curved or other non-linear form, or even in the form of a closed loop (for example a coil of wire), such elements being wrapped either singularly or in bundles, and the term "elongate article" as used herein is intended to encompass both such elements singly and bundles of such elements.
Conventionally, such articles are wrapped by means of one or more lengths of paper or the like which are wound helically around them using appropriate machinery, for example as shown in German Patent specification No. 2256708, so that adjacent windings overlap somewhat. In many cases such articles are relatively flexible, due often to their length, which may be some 6 or 7 meters for example. As a result flexing of the package gives rise to a tendency for adjacent turns of the wrapping to separate, thereby exposing the article to potential damage. To reduce this tendency it is often desirable for the adjacent windings to be adhesively secured together where they overlap. However with conventional wrapping systems this requires the application of a liquid or flowable adhesive substance, e.g. a glue, to the edge zone of the wrapping material as this is unrolled by the wrapping machine and laid onto the exterior surface of the article being wrapped.
The provision of such gluing apparatus naturally increases the cost of the machine, but there is the additional disadvantage that supplies of an appropriate adhesive are required to be maintained, and moreover the operational difficulties in maintaining the gluing apparatus to function properly under conditions of use is such that such apparatus has not met with commercial success.
The use of wrapping materials, coated with conventional adhesive materials of the kind which are tacky and adhere to most materials which are not specially treated has not generally been considered to be practicable because of the need for a release paper or the like between adjacent turns of the material in the roll on which it is supplied, and the adherance of contaminating material to any exposed area of said adhesive material on the wrapping material when in use, or the adherence of the wrapping material to the articles wrapped therein.
One proposal which attempts at least partially to overcome such drawbacks is described in U.S. Pat. No. 4,409,776. This involves using a wrapping material which has an adhesive coating on one face only and forming two layers of wrapping around the article, an inner layer in which the adhesive-coated face is presented outwardly and an outer layer in which the adhesive-coated face is presented inwardly. In this way, no adhesive material contacts the wrapped article, nor it is exposed externally. However, this method has several disadvantages. In particular, since two layers of wrapping are required, it uses twice the quantity of wrapping material which would be required by a single-layer wrapping technique. Specifically, in this proposal the second layer is formed by reversing the wrapping machine so that it is suitable only for batch operation rather than continuous wrapping. Alternatively, to adapt the method for continuous wrapping, it would be necessary to provide two wrapping machines, one for each layer, with consequent increase in capital and maintenance costs as well as extra space requirements.
The object of the invention is to provide an improved method of wrapping elongate articles which obviates or reduces the above-mentioned disadvantages.